Striking a Bullet with a Bullet: HOE

U.S. Army officials staring at their radar screens on June 10, 1984, watched in breathless anticipation as two American missiles—one launched from the Vandenberg Air Force Base in California, the other from a missile range in the Marshall Islands—hurtled toward each other far above the vast expanse of the Pacific Ocean.

This was the fourth and final flight test of the Homing Overlay Experiment (HOE) vehicle. The objective of this revolutionary experiment was for one missile to destroy another outside the atmosphere using only force of impact. This was important because the ability to destroy an enemy missile without explosive warheads on the interceptor missile would minimize lethal effects on the ground.

Having already attempted this new method of destroying a missile three times with limited success, the Army and its industry team, which included Lockheed Missiles and Space Company, knew this was the final opportunity to prove such an intercept was possible.

The first missile—a dummy warhead—had been deployed from California to mimic the trajectory of an intercontinental ballistic missile (ICBM) as it dashed northward toward a point 4,500 miles away, near Kwajalein Atoll in the Pacific.

When radar at Kwajalein picked up the incoming, unarmed ICBM, the Army team immediately launched a defensive missile the HOE with a non-explosive kill vehicle, to strike it head-on, nose to nose.

As one Army official put it, it was like trying to “hit a bullet with bullet.”

Defensive Measures

The stakes for success could not have been higher. Just a year earlier, President Ronald Reagan had announced his Strategic Defense Initiative (SDI), an ambitious effort to create a defensive “shield” against Soviet missile strikes. The HOE technology was a key linchpin in the plan, which sought to use a mix of space- and ground-based defensive weapons to protect the U.S. mainland.

The Army’s creation was different from previous defensive missile technologies, which relied on the detonation of a nuclear warhead to destroy everything within its blast radius. The HOE missile, by contrast, was free of nuclear materials, equipped instead with its own guidance system and a unique radial net that unfurled before contact, increasing the missile’s chance of striking the ICBM. Which is precisely what occurred over the skies of the Pacific on June 10, 1984. As the mock ICBM streaked toward its target, the HOE hit-to-kill vehicle locked onto its target and promptly unfurled its ribbed metal plates.

When the two missiles met, outside the atmosphere more than 100 nautical miles above the earth, the sheer force of the impact destroyed both missiles.

The world’s first successful non-nuclear missile defense interceptor had arrived. This achievement earned the government and industry team the 1986 American Defense Technical Achievement Award.

A Shield Against Aggression

Beyond showing that a non-nuclear defensive weapon was possible, the HOE kill vehicle proved that incoming missiles could be intercepted during the late stages of their descent.

Moving forward, Lockheed would use the revolutionary hit-to-kill technology that it pioneered with HOE to intercept missiles further and further away from their intended targets, both higher in the atmosphere using its Terminal High Altitude Area Defense, as well as near their launch sites with PAC-3 interceptor missiles.

Transferred from the ground to the sea, the hit-to-kill technology is at the heart of Lockheed’s Aegis ballistic missile defense, which will play a key role in the creation of a multilayered defense shield over Europe, bringing the project full circle in less than three decades.

In fact, all of today’s major U.S. missile defense systems, including those developed by other corporations, use the hit-to-kill, force-of-impact technology that HOE debuted, debunking the claims of critics that it was impossible.

Sources and Additional Reading

Collins, Martin. After Sputnik: 50 Years of the Space Age. New York: HarperCollins, 2007.

Walker, James A., Lewis Bernstein, and Sharon Lang. Seize the High Ground: The U.S. Army in Space and Missile Defense. Washington, D.C.: Government Printing Office, 2003.